An amphiphilic polymer network is a random assemblage of hydrophilic and hydrophobic polymer chains that is able to swell in both hydrophilic solvents (e.g., water) and hydrophobic solvents (e.g., a liquid hydrocarbon). Amphiphilic polymer networks are described, for example, in U.S. Pat. No. 4,486,572 to Kennedy (one of the applicants herein), and in Keszler and Kennedy, Journal of Macromolecular Science, Chemistry Edition, Vol. A21, No. 3, pages 319-334 (1984).
U.S. Pat. No. 4,085,168 to Milkovich et al. describes chemically joined, phase-separated self-cured hydrophilic thermoplastic graft copolymers which are copolymers of at least one hydrophilic (water soluble) ethylenically unsaturated monomer or mixture thereof and at least one copolymerizable hydrophobic macromolecular monomer having an end group which is copolymerizable with the hydrophilic monomer. The resulting copolymer is a graft copolymer characterized as having a comb-type structure consisting of a hydrophilic backbone polymer with hydrophobic polymer side chains bonded thereto. The side chains are disclosed as being bonded to the hydrophilic polymer at only one end of the side chain, so that no network results.